<!DOCTYPE html>  
<html>  
  <head>  
    <title>Comments</title>  
  </head>
  <body>  
    <script type="text/javascript">  
       // This is a comment
       document.write("Hello world <br>"); 
       
       document.write("Hello world <br>"); // This is a comment
       
       /*
         This is multiple comments
         This is multiple comments
       */
       document.write("Hello world <br>");
    </script> 
  </body>  
</html>